From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Letter from S.U. Carburetter Co. Ltd. about experimental work on pumps, specifically addressing valve noise and lift.
| Identifier | ExFiles\Box 149\4\ scan0124 | |
| Date | 24th February 1936 guessed | |
| THE S.U. CARBURETTER CO. LTD. CONTINUATION No...... 2. Messrs. Rolls-Royce Ltd. 6 volts with the original arrangement of a deep recess in the armature. So far we have had better results by shifting the core. Experimental work on these has been held up to some extent owing to the trouble you experienced with valve noises, as we have been concentrating on this matter more. We found that there is a tendency towards this on the majority of the pumps, and therefore we have had to take measures to cure it, as we should otherwise have been unable to anything like keep up with your requirements. The only cure is a reduced valve lift on the foot valve. The lift on the original was 35 thou. the lift on our standard type "L" pumps is 15 thou. We have experimented with a range of valve lifts and we find that the noise can be eliminated without any reduction in output on our test stand with a valve lift between 22 and 25 thou. We think that if we get no reduction under our conditions of testing, you will not get any on the actual job, as a reduced valve lift is going to have a bigger effect on a free flow than on the rather more restricted flow which you get on the car. Having got this matter clear, we are now carrying on experiments with the silence pumps. We will let you have these as soon as we are sure that they are satisfactory. Yours faithfully, For THE S.U. CARBURETTER CO. LTD. | ||